Despite Congress’ Best Efforts, Prisons Keep Shrinking

Congress failed this year (again) to pass criminal-justice reform legislation, despite strong bipartisan interest in curbing mass incarceration. Nevertheless, a Bureau of Justice Statistics report released Thursday shows that the U.S. imprisonment rate dropped for the seventh straight year in 2015, reaching its lowest level since 1997. How is the country sustaining progress on de-incarceration, congressional paralysis notwithstanding?

Author: Keith Humphreys

Keith Humphreys is the Esther Ting Memorial Professor of Psychiatry at Stanford University and an Honorary Professor of Psychiatry at Kings College Lonon. His research, teaching and writing have focused on addictive disorders, self-help organizations (e.g., breast cancer support groups, Alcoholics Anonymous), evaluation research methods, and public policy related to health care, mental illness, veterans, drugs, crime and correctional systems. Professor Humphreys' over 300 scholarly articles, monographs and books have been cited over ten thousand times by scientific colleagues. He is a regular contributor to Washington Post and has also written for the New York Times, Wall Street Journal, Washington Monthly, San Francisco Chronicle, The Guardian (UK), The Telegraph (UK), Times Higher Education (UK), Crossbow (UK) and other media outlets.
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No shout-out to the lead hypothesis popularised by Kevin Drum? If that's it, the fall should soon slow, as young people gave now all grown up lead-free, while the lead-addled older generation reach the age of criminal retirement. If it's from a change in policy and practice in criminal justice, the decline should continue.

From the article: "If the extraordinarily high violent crime rate of 20-year-olds in 1994 had been due to the character of that generation (i.e., people born in 1974), it’s very hard to explain how in 2004, when they were 30 years old, this “violent generation” was no more violent than were the 30-year-olds of 1984 (e.g., the generation born in 1954)."

Unless I'm reading the associated chart all wrong, the 20-year-olds of 1994 were about a third more violent than the earlier or later cohorts. At age 30 they were still about a third more violent. They only reached equality at age 40, when all violent crime has dropped to a low rate. The chart is quite consistent with a "cursed generation" effect, and hence with the lead hypothesis.

The years refer to calendar year, not cohort. In calendar 1994 (the grey line) people from the ages of 10 to 40 were very violent. 10 years later (yellow line) violence collapses across the lifespan, which should not have happened with a spoiled generation.

To take a concrete group, people who were born in 1974 are age 20 in 1994 where they look very violent. 10 years later in 2004 this *same generation* has the violent rate at 30 as did people born in 1954 (i.e., those who were 30 in 1984).